Electrical power generation, transmission and distribution relies on a number of transmission and distribution networks to transfer electrical power to a series of end users, as well as the generating equipment itself. Generating equipment includes the devices for generating the electrical power, most often an electrical machine such as for example a synchronous generator. Generating equipment also includes fuel cells, batteries such as used in an Uninterruptible Power Supply (UPS), solar cells etc. It also includes the devices necessary for actually bringing the power to the transmission or distribution networks, such as power transformers, instrument transformers, circuit breakers of various kinds, surge arresters etc., as well as secondary devices such as transducers, sensors and other devices needed for controlling the system. A transmission network can include high voltage lines or cables, both AC and DC, and a diversity of equipment meant to ensure the secure and reliable transmission of power, for example reactors, capacitors, Synchronous Condensers, Static Var Compensators, FACTS components, etc., and secondary devices as referred to above. Whereas transmission refers to the highest level in the hierarchy of systems that eventually deliver electrical power to end consumers, distribution networks are systems that are closer to end users, including both high voltage, medium voltage, and low voltage systems, medium voltage being defined as the lower levels of high voltage. A distribution network on high or medium voltage level will be similar to a transmission network. On the lowest levels of distribution, the voltage is typically transformed from medium voltage to low voltage, which is the level that ordinary consumers see. Such systems typically include medium voltage, low voltage and feeder sections with a diversity of switching equipment, substations, transformers, breakers, fuses, measuring and other electrical equipment situated in a diversity of locations, buildings and yards. This includes distribution equipment to more or less specialised equipment for industrial and commercial consumers, factories etc., as well as ordinary household consumers.
The background of this invention is in electrical power transmission and distribution networks, and in electrical power generation. The invention specifically also relates to generation and distribution functions of plants including smaller and less traditional generation means such as micro turbines, wind farms, Combined Heat and Power plants (CHP) and other often privately owned generators that supply power to the network in a distributed fashion.
Operations and operational service criteria may be classified not only by type of consumer, large or small for example. Factors of location such as rural, urban or city; criticality of supply, that is, supply for a hospital versus supply for a warehouse contribute to a diverse range of requirements for delivery of electrical power. The operation of such transmission and distribution networks demands a broad diversity of know how, organisation, maintenance, financing, development or expansion, spare parts, access to new equipment and technically skilled labour.
By tradition, and under conditions of a regulated market with state or community owned monopolies, a utility company is a company that operates and usually owns generating and/or transmission/distribution equipment. The utility company carries out a range of functions including maintenance of a network in accord with both present and future requirements. This is typically based on the utilities own business plan and carried out using primarily in-house engineering staff and other specialist professionals, supplemented as needed by outside sub-contractors and/or consultants to perform specific maintenance or more often installation tasks. As a result of a specific plan for maintenance for the network, maintenance work is carried out to ensure a planned level of service availability for the network and it's several power generation, distribution and power supply parts. In practice assets are owned and maintenance staff employed or allocated as or when needed to execute a maintenance plan designed to meet a present or forecast demand for electrical power.
However under de-regulation market conditions have led to a re-focusing of priorities as regards the requirement for maintenance of a transmission and distribution network to better meet present requirements and future requirements. First, maintenance is expected to be carried out under a more cost effective and predictable cost regime. Second, emphasis on meeting stringent power levels, power availability and power quality requirements set by regulatory authorities, together with a generally reduced investment in installed plant throughout the industry, demands maintenance that shall provide solutions that comply with both stringent technical and financial demands. One such approach is called RCM—Reliability Centred Maintenance.
Third, the increased focus on distributed, environmentally friendly generation, is leading to growing numbers of smaller and unconventional power plants such as micro turbines, Combined Heat and Power (CHP) plants, wind farms, tidal water or ocean wave plants, solar cell plants, and Fuel Cell plants, being connected to power grids. At the same time, components such as power lines and transformers are increasingly being operated closer to their physical, often thermal, limits. This makes the power system itself, and its operation and maintenance, more complex. For example, operating power lines closer to their thermal limits at the same time as new asynchronous wind parks are connected to the grid destabilises the power system, and increases the risk of error. Another example is that the connection of a large number of small, often single phase, generators makes it more difficult to carry out network control functions such as balancing loads in parts of the network, thereby also increasing the risk of error.
Fourthly under de-regulated market conditions the owner or operator of a power distribution network may not be a traditional utility company with experience of running and maintaining such networks. For such a new owner/operator the provision of maintenance in an effective and economic way without the benefit of access to internal know-how may be difficult.
Thus, utilities and operators are faced with the challenge of delivering high quality, reliable electric power at competitive rates to their customers using limited manpower and resources. This calls for devices, systems and methods that can provide maintenance of a power system in a cost-effective and reliable way.
A document available from enervista.com (Trade Mark) describes an approach to substation management for municipal utilities and rural co-operatives that includes the use of Internet-technology. A system is described with modules with names such as eSCADA and eEXPERT. With an eSCADA module, substations are equipped with a Universal Relay provided by General Electric (GE), and monitored via a Web-interface. When an error in the system occurs, an alarm and error message appears in a Web-browser included in eSCADA, and certain information on the fault is available. Associated with the fault information is the eEXPERT module, which is a knowledge base with public documents and internet links to websites of standards, application papers, notes and diagnosis guides, as well as proprietary procedures and documents. One advantage is stated to be a significant speed-up of outage restoration by less-experienced staff. It is also mentioned that if a fault or early warning is detected by a regional operator, an engineer could be contacted to access settings, events at time of trip etc to assist in recommending suitable corrective actions. It also is described that a repair crew, prior to heading out, can get exact details of what equipment has failed, where it is, and the nature of the problem. It is also mentioned that the crew can call up and print stored documents such as network configuration, wiring diagrams and maintenance procedures.
The advantage of the system described seems to be limited to that the Utility itself has a presumably cheaper software system for substation management, cheaper because of the utilisation of the ubiquitous Internet-technology instead of expensive proprietary SCADA software and custom programming. However in a context of providing cost-effective maintenance to ensure a reliable supply of high quality electrical power the description is limited in that it only addresses response to power outages of the sort caused by weather damage to equipment. For example, the description does not describe how less-experienced staff may be enabled to carry out repair or maintenance tasks.